feat(gateway): add Seedream 5.0 Pro

apps/api/internal/runner/param_processor_media.go

@@ -722,10 +722,13 @@ func (imageCountProcessor) ShouldProcess(params map[string]any, modelType string
 
 func (imageCountProcessor) Process(params map[string]any, modelType string, context *paramProcessContext) bool {
 	capability := capabilityForType(context.modelCapability, modelType)
-	if capability == nil || !boolFromAny(capability["output_multiple_images"]) {
+	if capability == nil {
 		return true
 	}
 	maxCount := int(math.Round(floatFromAny(capability["output_max_images_count"])))
+	if !boolFromAny(capability["output_multiple_images"]) {
+		maxCount = 1
+	}
 	if maxCount <= 0 {
 		return true
 	}

apps/api/internal/runner/param_processor_test.go

@@ -662,6 +662,31 @@ func TestParamProcessorImageResolutionAndOutputCount(t *testing.T) {
 	}
 }
 
+func TestParamProcessorForcesSingleImageWhenMultipleOutputsAreDisabled(t *testing.T) {
+	body := map[string]any{
+		"model":  "Seedream-5.0-Pro",
+		"prompt": "draw",
+		"n":      4,
+	}
+	candidate := store.RuntimeModelCandidate{
+		ModelType: "image_generate",
+		Capabilities: map[string]any{
+			"image_generate": map[string]any{
+				"output_multiple_images":  false,
+				"output_max_images_count": 1,
+			},
+		},
+	}
+
+	result := preprocessRequestWithLog("images.generations", body, candidate)
+	if result.Body["n"] != 1 {
+		t.Fatalf("single-output image model should force n=1, got %+v", result.Body)
+	}
+	if len(result.Log.Changes) == 0 || result.Log.Changes[len(result.Log.Changes)-1].CapabilityPath != "capabilities.image_generate.output_max_images_count" {
+		t.Fatalf("single-output adjustment should be logged against output_max_images_count, got %+v", result.Log.Changes)
+	}
+}
+
 func TestParamProcessorImageSizeConstraintsNormalizeExplicitDimensions(t *testing.T) {
 	body := map[string]any{
 		"model":      "doubao-5.0图像编辑",